Flaming Taps: Methane Migration and the Fracking Debate

December 19, 2011 | 12:57 PM

Methane migrated into Dimock resident Norma Fiorentino's water supply, causing her water well to explode. DEP later blamed Cabot Oil and Gas.

One of the most iconic symbols of the fracking debate is the video of a man setting his tap water on fire in Colorado.

Fracking, which refers to hydraulic fracturing, is a technique used to extract natural gas, and has become synonymous with all things gas drilling. It involves shooting water, sand and a mix of chemicals at high pressure deep into a wellbore to help split the shale rock and release the gas.

Some worry fracking fluid will leak out of a well and contaminate aquifers. In fact, a recent draft EPA study about water pollution in Pavilion, Wyo., does make that link. Fracking wastewater has also spilled and contaminated surface water.

But fracking does not put methane into tap water. Tap water blow torches, as seen in the documentary film Gasland, result from methane migration. Such movements of gas may or may not be related to drilling. But they do not result from fracking. And that’s an important distinction to make.

Tracing the source of migrating methane, or stray gas, can be complicated and mysterious. Investigators often use isotope identification to get a “fingerprint” of the gas. But just as in law enforcement, fingerprints can be tricky.

When a wellbore is drilled, a steel casing is sent down the hole. Then cement is poured down, and pushed upward to seal the open space between the steel casing, and the rock. That cement seal is supposed to prevent any gas, or fluid, from migrating into or out of the wellbore, and from using that space between the rock and the newly drilled well as a conduit. But that cement job doesn’t always work. And in the case of Dimock, it failed miserably.

Fred Baldassare worked as an inspector for DEP, where he spent six years investigating methane migration and helped out on the Dimock case. He was the guy who looked at the geochemistry of those flaming taps. In other words, he looked at the gas fingerprint. Baldassare says the evidence linking Dimock’s flaming tap water to gas drilling by Cabot is overwhelming.

But where that gas actually came from, whether it was from deep in the Marcellus formation, or whether it was from a more shallow formation, is unclear.

“The gas was nearly an exact match to the gas coming from the Marcellus wells,” said Baldassare. “But we couldn’t say it came from there because there are gas deposits above the Marcellus that have the same fingerprint.”

And that’s where it gets tricky. One big problem in Pennsylvania is this: Without a baseline water test before any drilling activity begins, how does one prove high levels of methane didn’t already exist in the water well i.e. from natural migration? And few residential wells in the state have those pre-drilling readings.

Gas can get into well-water in various ways. Baldassare says drilling, along with a bad cement job, can cause any gas pocket that has been stable for thousands of years to start moving. That’s because methane, under high pressure, wants to go to an area of lower pressure. And drilling, whether it’s a vertical well, horizontal well, deep well, or shallow well, can provide that opportunity.

But other things can, too, such as coal mining. It can also happen naturally. And that’s where the importance of establishing that gas fingerprint comes in. Baldassare says he spent a lot of time tracking methane migration long before the first Marcellus Shale gas well was even drilled.

“There are examples of [methane migration] throughout the Northeast that have nothing to do with gas activity,” says Baldassare. “And there are others that do happen because of drilling or mining activity.”

Reports of methane migrating into water wells date back to the 1800′s. It can originate in a coal bed. A report put out by the Penn State Cooperative Extension Service in 2009 says deep water wells in the northern and western parts of the state are the most susceptible. Still, the study also says natural methane migration is a rare occurrence.

When methane migrates, it will dissolve in water, but once the water reaches a lower pressure zone, the gas wants to get out. That’s why people experiencing methane in their water supplies will first notice a spurting at the tap, or bubbles in a glass of water. If that happens, the concentration is high enough to be combustible and the presence of the colorless, odorless methane becomes a danger.

If it’s above 28 milligrams per liter, it’s considered dangerous, and can collect in a tight space. When triggered, it could explode. That’s what happened when Dimock resident Norma Fiorentino’s water well blew up.

Neither the federal EPA nor the state DEP consider drinking water with methane to be harmful. But there are few studies on the long-term health impacts of drinking water with high levels of methane.

Recent studies on the connection between methane migration and gas drilling has produced conflicting conclusions. Duke University researchers published a report in May, 2011 that found higher concentrations of methane in water wells near gas drilling sites in Pennsylvania. But another study, published by Penn State University in October 2011, found no correlation between the presence of natural gas wells and the presence of methane in drinking water.

The dueling studies have fueled confusion over the link between flaming taps and natural gas drilling. In December 2011, the EPA published a draft report on water pollution in Pavilion, Wyo. In that report, the EPA says methane migration may be due to gas drilling.

“Although some natural migration of gas would be expected above a gas field such as Pavillion, data suggest that enhanced migration of gas has occurred within ground water at depths used for domestic water supply and to domestic wells. Further investigation would be needed to determine the extent of gas migration and the fate and transport processes influencing migration to domestic wells.”

So once methane migrates into a water supply, what then? Baldassare says proper venting and aeration does work. But some homeowners suffering from high levels of methane in their water wells have expressed doubts about the venting systems, as well as filtration systems. Baldassare also says if the source of the stray gas is halted, eventually, the water will be free of the methane through natural processes. But it’s unclear how long that could take.

Comments

Dory Hippauf

Regarding Duke Study vs Penn State study – Penn State study was funded by gas industry, so it should come as no surprise the results favored the gas industry.

Susan Phillips

Dory, the Penn State study on methane migration was not funded by industry. It was funded by the Cen­ter for Rural Penn­syl­va­nia and the Penn­syl­va­nia Water Resources Research Cen­ter. The state leg­is­la­ture funds the Cen­ter for Rural Penn­syl­va­nia, and the U.S. Geo­log­i­cal Sur­vey sup­ports the Water Resources Research Center.
Susan Phillips

Timothy Canny

Wouldn’t one expect to find more methane in water wells where drilling occurs for the same reason that drilling is occuring – the presence of large deposits of natural gas? Just as the story suggests, you need pre-drilling studies to determine whether the large deposits of natural gas and natural migration of methane into the water wells from these deposits is the issue and/or if drilling is then having any noticable effect.

Sally G

Certainly one needs predrillng studies; the problem is that such evaluations are not required when a lease is signed, and the company has no interest in doing one—it could only hurt the company to have specific measurements. The property owner, whom it has the potential to beenefit if something goes wrong, is not always aware of the potential problems—alathough I am sure that is changing now as publicity is more widespread.

Gwhite

The FACT is that many of the GAS COMPANIES are testing well water before they start drilling to protect themselves from lawsuits BECAUSE THEY KNOW THAT FRACKING IS SAFE.

jim

It’s state law. They have to test the water. That happened because they know it causes problems.

http://twitter.com/qaqcpipeman Donald L Crusan

Kinda redundant to blame fracking. Growing up in rural Westmoreland County, PA, we as redneck farm boys had fun lighting “gas” coming out of the ground around the old mines that had been abandoned. This was in the 1950s also. Gas lines ran on top of the ground and we never had any problems. I remember vividly some of this fun stuff,

Sally G

This seems to be a pretty transparent attempt to decouple fracking and methane in water supply—what is the biggest change in activity? Fracking. And whether it comes form the drilling of the well or a problem with the casing, neither of those factors are unrelated to fracking; they are part and parcel of that process. To me, this is a specious arguement.

Susan Phillips

Hi Sally, the point is that drilling, whether or not fracking is used, can cause methane migration. Fracking refers to a process of breaking up rock in order to release gas held in tight formations. That’s done after a well is constructed. Some have experienced methane migrating into their water supplies before any fracking occurred, and when no fracking occurred. Fracking may be new to Pennsylvania, but drilling for gas is not, and neither is methane migration.
Susan Phillips

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About StateImpact Pennsylvania

StateImpact Pennsylvania is a collaboration between WITF and WHYY. Reporters Marie Cusick and Susan Phillips cover the fiscal and environmental impact of Pennsylvania’s booming energy economy, with a focus on Marcellus Shale drilling. Read their reports on this site, and hear them on public radio stations across Pennsylvania.